Method of processing raw wood



y 1958 J. F. T. BERLINER METHOD OF PROCESSING RAW WOOD Filed July 21,1954 iZZ/QZZZEOZ" (fa/245 Ff fierZz'zzer United States Patent METHOD OFPROCESSINGRAW WOOD Julius F. T. Berliner, Chicago, Ill.

Application July 21, 1954, Serial No. 444,787

Claims. (Cl. 144-309) This invention relates to a method of processingraw wood, and more particularly to a method adapted to the preparationof the wood of shrubs such as those found in desert regions, for use inthe production of hardboard and for the recovery of lay-products fromthe wood.

In the development of a new fiber-board material and a process of makingsuch material from certain desert shrubs, including the creosote bush,as described in detail in my co-pending application Serial No. 442,637filed July 12, 1954, for Fiber Board and Process of Making Same FromDesert Shrubs, it was found desirable to remove as much as possible ofthe barkfrom the wood, because the presence of such bark tends to effectthe formation of a mud during the processing of the wood fibers, whichmud materially retards the rate of formation of the fibrous mat in theprocess of forming the material into a sheet, and also darkens the colorof the resultant board product. As initially cut, the shrubs are severedfrom their root growth close to the ground. As an early step in thepreparation of the wood for :use, it is chopped or cut into pieces ofvarious sizes and shapes ranging generally from 2 inches to 5 inches inlength and having the shapes and lateral dimensions of normal growth.

The creosote bush, which has been found to be very satisfactory incharacteristics for adaptation to the production of hardboard, hasrelatively thin bark which clings tenaceously to the wood, and which isbrittle and has little or no fiber structure. The characteristics of vthe bark and the irregularity of the sizes and shapes of the woodpieces, in addition to the generally small diameters of the wood pieces,all contribute to the difficulty of the problem of elfecting the removalof a satisfactory proportion of the bark from the wood. It is natural,of course, that since the wood without its bark is a usable portion ofthe plant, for the production of board, the waste of the wood in theprocess of removing the bark is to be minimized. Furthermore, it isdesirable that the process of effecting removal of the bark shall leaveboth the wood and the bark in separable and recoverable conditionwithout necessitating the drying of either or both, or other suchpreparatory operations.

Washing and floatation of cooked bark from digested wood chips proved tobe unsatisfactory methods of separating the bark from the wood fibersand their constituents, since the constituents of the wood fiber areusable with the fibers in my process for the production of board. Also,wet tumbling of the wood chips in a pebble mill was found to result inan undesirable high loss of the wood fibers. it being readilyunderstandable that the production of fiber-board in quantitynecessitates the processing of very large volumes of wood chips of thetype to which reference has been made, it is the general object of thisinvention to provide a method for effecting the removal of at least alarge proportion of the bark from irregularly shaped and relativelysmall pieces of the wood of the desert shrub, such as the creosote bush,and for elfecting the separation of the removed bark particles from thewood pieces.

My invention has for another object the provision of a method foreffecting the removal of a large proportion of the bark from pieces ofcreosote bush wood and the like without loss of an appreciable amount ofwood fibers or the natural constituents of the Wood.

Another object of my invention compre-hends the'pi o vision of a methodof removing bark from the wood of desert shrubs, which method leavesboth the wood and the bark inseparable and recoverable conditions.

As another object this invention has within its purview the provision ofa method of efi'ecting the removal of the bark from large quantities ofrelatively small and irregularly shaped pieces of the wood of thecreosote bush in a manner which is practically continuous in itsoperation.

Other objects and advantages of the invention will be apparent from thefollowing description and'the accompanying drawings in which similarcharacters of reference indicate similar parts throughout the severalviews.

Referring to the singlesheet of drawings,

Fig. 1 is a diagrammatic view depicting apparatus adapted to use incarrying out the steps of my method as disclosed herein; and

Fig. 2 is a fragmentary front elevational view of a detail of a part ofthe apparatus depicted in Fig. 1.

In the exemplary embodiment of my method for processing raw wood whichis disclosed herein for illustrative purposes, wood of a desert shrub,such as the creosote bush found in desert regions of the southwesternUnited .States,.is gathered by being out of? near the surface of theground. For convenience in handling, hauling and storage, a portablemachine is utilized for chopping the Wood of the cut shrubs into pieceswhich are preferably from about 2 to 3 inches in length. Sincepractically all of the wood of the creosote bush is usable for theproduction of hardboard products, the cut portions or pieces of thestems and branches vary from about 1 inches to A of an inch in diametershapes. The Wood pieces which are thus gathered from the place of growthof the shrubs are hauled to a suitable place near the mill where theyare to be: utilized, and are placed on a stockpile which, in thedrawing, is indicated at 10. From the stockpile 10, the wood pieces arecarried on a conveyor 12 and fed into a hopper 13 which comprises theentrance to a debarking machine, indicated generally by the referencenumeral 14. From an outlet opening 15 of the debarking machine, thepieces of wood from which the bark has been substantially removed andthe finely divided particles of bark are discharged onto a screen 16 forseparation of the bark particles from the wood pieces. The barkparticles pass through the screen and into a hopper 17, from which theyare discharged through a conduit 18. The wood pieces'p'ass from thescreen 16 into a hopper 19 and are conveyed therefrom to a digester orplace of treatment through a conduit 20.

It may be understood that since the bark of thecre'osote bush has littleor no fiber structure and isremoved, in my process, in a dry state, bymechanical action which leaves the wood pieces intact, the barkparticles may be separated from the wood pieces by the action of ablower, instead of the screen separator depicted in the drawing. Ineither instance, the dry wood pieces and the dry bark particles areseparated and separately gathered for further treatment, as desired, andare in a dry state, ready for use, and there are no problems arisingfrom the dissolving of soluble constituents of either the bark or thewood, which constituents are desirably left in the wood and are ofirregular and bark for the further treatment. For effecting the removalof at least a very large proportion of the bark from the wood pieceswithout appreciable loss of wood and by mechanical method which does notrequire washing or water separation, I utilize a disk type mill 22having a housing 23, which housing encloses relatively movable plates 24and 25 which are in spaced, opposed and face-to-face relationship withone another, and at least one of which is driven through a shaft 26 by aprime mover such as an electric motor 27. In the disclosed debarkingmachine, the plate 25 is supported from the motor shaft 26 by a disk 28,and is thereby driven at relatively high speed with reference to theplate 24; the latter plate'being stationary and secured to the housing23.

Wood pieces having the bark thereon and fed into the hopper 13 flow intothe mid-portion of one end of the housing 23' and are moved outwardlybetween the op posed and spaced surfaces of the plates 24 and 25 by bothfrictional and centrifugal forces. As depicted in Fig. 2, the opposedfaces of the plates 24 and 25 have a multiplicity of teeth 29 projectingtherefrom to effectively roughen the operating surfaces of the plates,whereby those plates not only provide impact and a beating action on thewood pieces, but also cause the wood pieces to be beat and batteredtogether. The resultant flexure of the wood pieces and the impactsencountered by the pieces, as well as the friction of the pieces betweenthemselves and against the disks cause the bark to be broken intoparticles and separated from the Wood, after which the wood pieces andbark are finally thrown outwardly against the interior of the housing 23for relatively heavy impact against that housing to further insure theremoval of the bark from the wood. The separated bark and the debarkedwood pieces flow outwardly by gravity through the discharge opening inthe housing.

Since centrifugal force and impact are utilized for the loosening andseparating of the bark from the wood, the rotary disk of my debarkingmachine is driven at relatively high speed. A speed of 3600 R. P. M. hasbeen found to be satisfactory. For effecting the debarking of woodpieces of the sizes referred to, it has been found that a separation ofbetween /2 inch and 1% inch is between the surfaces of the plates 24 andis satisfactory. The wider spacing leaves some bark on the wood andincreases the speed of movement of the wood pieces through the debarkingmachine. It also results in less loss of wood as a result of thegrinding action which occurs in the operation. An average spacing offrom inch to A; inch accomplishes very satisfactory results.

From the foregoing description, it may be understood that my disclosedprocess of preparing raw wood of desert shrubs, such as the creosotebush, for use in the production of hardboard products and the likeincludes the steps of severing the wood portions of the shrubs intorelatively small pieces, removing the bark from the wood pieces withoutappreciable loss of wood fiber by mechanical means utilizing frictionaland impact forces to flex, tumble and batter the wood pieces so as toloosen and remove the bark therefrom, and then separating the woodpieces from which the bark has been removed from the particles of bark.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. The process of preparing the wood of a desert shrub for use in theproduction of a hardboard product, which process comprises the steps ofsevering the natural woody parts of the shrub into pieces of naturallateral shape and of a few inches in length, feeding the severed piecesinto the midregion of a disc type mill having at least one revolvingdisc driven at a speed such that the pieces are thrown outwardly bycentrifugal force so as to be battered together while being tumbled andcontacted with impact force by the disc, whereby the bark is broken intoparticles and removed from the wood.

2. The process of preparing the wood of a desert shrub for use in theproduction of a hardboard product, which process comprises the steps offorcefully battering together and abrading relatively small pieces ofthe wood in a normally dry state between relatively moving plates havingrough surfaces in spaced relationship to one another and having a speedof relative motion sufiicient to shatter and loosen the bark by impact,thereby to effect removal of a large proportion of the bark from thewood.

3. The process of preparing the wood of a desert shrub for use in theproduction of a hardboard product, which process comprises the steps offorcefully battering together and abrading relatively small pieces ofthe wood in a normally dry state between plates having rough surfaces inspaced relationship to one another and which move relative to oneanother at high speed, thus affording impact sufficient to shatter andloosen the bark, thereby to effect removal of a large portion of thebark from the wood, the said battering together and abrading of the woodpieces constituting a continuing operation as a result of a flow of thewood pieces between the relatively moving plates.

4. The process of preparing the wood of a desert shrub for use in theproduction of a hardboard product, Which process comprises the steps ofsevering the natural woody parts of the shrub into relatively shortpieces of natural diameters, and effecting removal of a lar e portion ofthe bark from the wood pieces by mechanical and forccful battering ofthe pieces together at high speed to provide impact sufficient toshatter and loosen the bark, and abrading the pieces to remove theshattered and loosened bark while the wood is in a normally dry state.

5. The process of preparing the wood of a desert shrub for use in theproduction of a hardboard product by the removal of bark therefrom,which process comprises the steps of forcefully battering together andabrading relatively small pieces of the wood in a normally dry statebetween metal discs in spaced and opposed relationship and movingrelative to one another at a high speed which is sufficient to provideimpact which shatters and loosens said bark.

References Cited in the file of this patent UNITED STATES PATENTS632,979 Wolfe Sept. 12, 1899 1,120,631 Schenck Dec. 8, 1914 1,247,526Ginettley Nov. 20, 1917 1,877,517 Macartney Sept. 13, 1932 2,558,574Martin et a1. June 26, 1951 2,596,015 Dunwoody May 6, 1952

